not your everyday carb problem

[hobgoblin351]

Hey guys whats up? It's been awhile, but I finally got the stang painted. and it looks great! Yeah I know I'll get some pics in here eventually. So now it's time to work out some of the bugs.
I'm running a Boss351 with a pretty big cam. An Excellorator manifold with a 750 double pump mech 2nds on top. Sounds like a good setup right? I'm running hopelessly rich. I tried playing with the idle mixture, and rejetting. Still I foul plugs. Changed them 5 times this past summer, always black. I even tried a buddies 650 same result.
The 3 books I've read on Holley's have a total of about 3 pages on power valves. I'm leaning toward them as the source of my problem. All the books say that I should be making enough vac at idle to keep them shut. You raise your RPM's and the manifold vac drops and they open up. My problem is that my manifold vac does not drop off it goes up! I used a friend's gauge and checked every vac port. I'm running close to 10 at idle and it goes up with the RPM's. I'm going to buy a new gauge myself just incase his was screwed up. ( But I dont believe it was. The high vac readings would also explain the tranny shifting problems I'm having.)
Now there were two lines in one of the books that said in certain cases if you're running too small a carb on a big cammed engine this can occur. Is this true? Something about the engine wanting to suck large amounts of air/fuel mix throught a small carb port would lead to very high vac readings that dont back off. I'm thinking that because I cant get my engine to idle under 1000rpm, it never makes the low vac needed to keep the valve shut. Instead it idles around 1200 and the valve is always open. Am I on the right track with this? I'm running out of ideas.